In my U.S. Pat. No. 4,096,601, for example, and elsewhere there are described multipurpose rug and carpet cleaning heads having a plurality of units which may be made effective to carry out various rug or carpet cleaning tasks. It is, for example, known to provide a rotating brush (brush unit), a foam applicator which can include a second rotary unit adapted to generate foam from a liquid canister dispensed onto the carpet, a suction device capable of drawing liquid or air from the surface of the carpet, and various ancillary means such as a valve or dispenser for the liquid, a bag, canister or other holder for dry soil, a container for wet soil or liquid drawn from the carpet and various means for placing the selected units in operation.
Switch levers for the latter purpose, for example, are provided on the housing or floor-treating head and on the handle for displacing the head and generally operate respective cables such as Bowden lines, for coupling the unit which is to operate with a rotary drive having a fixed axis in the housing of the head.
The difficulty with this arrangement is that it is of complex construction and difficult or complex to operate, since a respective switch element is required for each unit which can be placed in or cut out of operation.
Because of the complexity of earlier switching devices, moreover, the head usually must be of inconveniently large dimensions and weight.
Furthermore, where a number of units are selectively coupled to a given drive by transmissions which can be switched on or off, problems are encountered with wear of the transmission parts.